An IT product specification is

a document that outlines the features, functions, and requirements of a software or hardware product. While it is not mandatory to have a product specification in place, it is highly recommended for several reasons.
First, a product specification helps to ensure that all stakeholders have a clear understanding of what the final product should look like, what it should do, and how it should perform. This helps to reduce the risk of misunderstandings and miscommunication throughout the development process.
Second, a product specification provides a roadmap for the development team. It helps to ensure that they are working towards a common goal and that they are on the same page when it comes to the product's requirements and design.
Third, a product specification helps to prevent scope creep. This occurs when stakeholders start to request additional features or changes to the product after the development process has already begun. With a product specification in place, changes can be evaluated against the original requirements and design, helping to ensure that the product stays on track.
In conclusion, while an IT product specification is not mandatory, it is a highly recommended tool that can help to ensure a successful product outcome. Our IT company, KRTN®, uses a CEDIS methodology which includes creating an IT product specification as a part of the development process.